Explanation: This composite image features classic portraits of members of one of
the Solar System's most prominent families -
Jupiter and its four large
"Galilean" moons.
Starting from the top the moons are
Io,
Europa,
Ganymede, and
Callisto.
The top-to-bottom order is also the order of increasing distance from
Jupiter.
These are big moons indeed which attend
the largest planet.
The smallest of the lot, Europa, is the size of
Earth's moon while
Ganymede is the largest moon in the Solar System.
In fact, Ganymede with a diameter of 3,100 miles, is larger
than the planets Mercury and
Pluto.
The swirling
Great Red Spot appears at the edge of Jupiter.
A hurricane-like storm system that has persisted for over 300 years,
two to three earths could fit inside it.
Battered Callisto's
image was recorded during the 1979 flyby
of Voyager.
The other portraits were taken by
the Galileo spacecraft which began
exploring the Jovian system in 1995.